A Comparative Study of Mathematical Models for Migration of Pesticides in Surface and Subsurface Waters

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Abstract

Development, validation, and application of mathematical models for evaluating fate and transport of pesticide in the environment have received considerable attention during recent years. Mathematical modeling provides a conceptually valid and meaningful approach to integrate environmental properties and
chemical processes affecting ecological and/or human health. Additionally, modeling results can be used by Federal and State
Regulatory Agencies to support registration decisions or generally planning decision-making efforts. A part of this comprehensive management-oriented modeling process is the simulation of transport and transformation of
pesticides in agricultural watersheds. A number of models have been developed during the last decade and are used widely as
predictive tools for assessing the impact of pesticides on surface and groundwater quality. Usually these models are used as screening tools to evaluate a new pesticide or an existing one used in a specific agricultural area which may pose an environmental problem. The models are also useful as management tools for assessing the effects of agricultural management practices on non-point source pollution control. In this study, comparisons between two well known pesticide loading models are performed. Model predictions are compared
for a number of parameters, including surface runoff, soil erosion, and mass transport of two herbicides in surface runoff and in the soil profile. Given the ability of both models for potential use for
environmental risk assessment problems, historical data were used in order to estimate frequency distributions of the pesticide mass reaching the edge of the field and leaching from the crop root
zone.